ocfs2: tighten up strlen() checking

This function is only called from one place and it's like this:
	dlm_register_domain(conn->cc_name, dlm_key, &fs_version);

The "conn->cc_name" is 64 characters long.  If strlen(conn->cc_name)
were equal to O2NM_MAX_NAME_LEN (64) that would be a bug because
strlen() doesn't count the NULL character.

In fact, if you look how O2NM_MAX_NAME_LEN is used, it mostly describes
64 character buffers.  The only exception is nd_name from struct
o2nm_node.

Anyway I looked into it and in this case the domain string comes from
osb->uuid_str in ocfs2_setup_osb_uuid().  That's 32 characters and NULL
which easily fits into O2NM_MAX_NAME_LEN.  This patch doesn't change how
the code works, but I think it makes the code a little cleaner.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>